Polytriazoles are considered as an excellent high-performance polymer due to their outstanding set of properties. The current investigation reports the synthesis of a phosphorus-containing fluorinated diazide monomer, that is, bis[4-(4′-azidophenoxy)-3-trifluoromethyl phenyl] phenylphosphine oxide (PFAZ) and utilization of this compound to synthesize a set of trifluoromethyl groups and phosphine oxide containing sulfonated polytriazoles (PTPFBSH-XX). The copolymers with a different level of sulfonation (-XX = −60, −70, −80, −90) were prepared by the Cu(I) catalyst-assisted click reaction of equimolar amounts of a dialkyne (BPALK) and a mixture of diazides having one sulfonated diazide (DSAZ) and PFAZ. The polymers were further characterized by NMR ( 1 H, 13 C, 19 F, and 31 P) and FTIR spectroscopy. Freestanding membranes were attained from the dissolved copolymers solution in DMSO by standard solution casting route. The membranes showcased acceptable thermal and mechanical stabilities, excellent water management with a high proton conductivity, and outstanding oxidative stability. SAXS, TEM, AFM, and cross-sectional FE-SEM studies of the membranes indicated phase-separated morphology. The oxidative stabilities of the membranes ranged over 18 h. The polytriazole PTPFBSH-90 (PFAZ/DSAZ/BPALK = 10:90:100, where the degree of sulfonation is 90%) having a weight-based ion exchange capacity (IEC W ) of 2.39 mequiv g −1 exhibited a high proton conductivity of 142 mS cm −1 under hydrated conditions at 90 °C. Furthermore, PTPFBSH-XX polymer membranes displayed a comparable performance in microbial fuel cell as Nafion117. The chemical oxygen demand removal results indicated that the polymeric membranes could be sustainable in bioelectrochemical systems.

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A phosphaphenanthrene-based diazide monomer, 1,1-bis-(4-azidophenyl)-1-(6-oxido-6H-dibenz⟨c,e⟩⟨1,2⟩oxaphosphorin-6-yl) ethane (DPAZ), was synthesized via diazonium compound formation. DPAZ was used as one of the comonomers along with a sulfonated diazide to prepare a series of sulfonated polytriazoles (PTDPBSH-XX, where XX denotes the molar percentage of the sulfonated diazide in the diazide mixtures) through copper-induced click polymerization with the bisphenol-based dialkyne (BPALK). The products were analyzed using Fourier transform infrared (FTIR) and NMR techniques. Size exclusion chromatography (SEC) results indicated the formation of high molar mass products (weight average molecular weight as high as 74 900 g mol–1 with a polydispersity index (PDI) of 2.13). The polytriazoles showed high thermal stability, and the solution cast membranes from dimethyl sulfoxide (DMSO) were flexible and had good mechanical integrity. PTDPBSH-XX copolymers displayed high proton conductivity (141 and 152 mS cm–1 at 80 and 90 °C, respectively, for PTDPBSH-90 with a weight-based ion exchange capacity (IECW) of 2.46 mequiv g–1) with balanced water management and high oxidative stability (>16.5 h). The images of the cross-sectional membranes obtained from atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) studies revealed hydrophilic–hydrophobic phase-segregated morphology. Besides, the microbial fuel cell performances of the membranes were comparable with that of Nafion 117.

This work reports the synthesis and characterization of a series of new sulfonated copolytriazoles. The polymers were prepared by CuI catalyzed 1,3‐cycloaddition reaction of an equimolar amount of a dialkyne monomer, 1,3‐diethynylbenzene and a mixture of two diazide monomers, namely, 4,4′‐diazidodiphenyl ether and 4,4′‐diazido‐2,2′‐stilbenedisulfonic acid disodium salt. The copolymers showed high inherent viscosity indicating the formation of high molar mass product. The copolymers were characterized by Fourier transform infrared and proton nuclear magnetic resonance spectroscopic techniques. The copolymer membranes displayed moderate water uptake, high dimensional, mechanical, and thermal stability. Transmission electron microscopy micrographs displayed excellent phase‐separated morphology along with very fine ionic clusters. The copolymer PTEOSH‐90 (90% degree of sulfonation) showed much higher proton conductivity value which is up to 196 mS cm−1 at 80 °C in completely hydrated condition compared to that of Nafion (165 mS cm−1). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48514.

The semifluorinated sulfonated polytriazoles could integrate the benefits of both enhanced proton conductivity and chemical stability, which makes them one of the best choices for the fabrication of proton exchange membranes (PEM) for fuel cell applications. Herein we report a series of semifluorinated sulfonated polytriazoles, prepared from 2,2′-hindered pyridine functionalized nonsulfonated diazide (PYFAZ) and dialkyne (PYAK). The degrees of sulfonation of the polytriazoles (PYPYSH-XX) were varied by using DSSAZ as one of the sulfonated diazide comonomer in the polymer synthesis. The polymers showed a weight-average molecular weight of up to 450 800 g·mol–1, and their chemical structures were confirmed by FTIR and NMR techniques. The solution cast membranes showed phase-separated morphology with well-defined hydrophilic and hydrophobic domains. The membranes were mechanically robust (tensile strength up to 65.5 MPa, Young modulus of 2.37 GPa), were thermally stable, and exhibited a very high oxidative stability of 48 h (PYPYSH-70). The elongation at the break of the membranes was above 13%, somewhat lower in comparison to that of Nafion-117. Nevertheless, it was possible to fabricate a good quality electrode membrane assembly. The membranes show proton conduction in the range of 95–184 mS·cm–1 (80 °C) and a power density of 599–966 mW·cm–2 (H2/O2) depending on their degree of sulfonation. All these results indicate the potential use of these membranes in PEMFCs.